Importance of Dry Matter Intake

July 9, 2018

Dry matter (DM) is an important metric as calculations for balanced diet are based on a dry matter (DM) basis. Requirements of animals are defined on a DM basis and it eliminates effects of moisture on different feeds. That way, it brings everything to a common denominator.

Cows have high requirements of nutrients but the rumen has a limited capacity.

This makes it difficult to balance as the goal is to try and pack a lot of energy and protein sources while keeping good levels of fibre for rumen health.

When formulating for diets, it is standard practice to formulate in terms of density.

For example, calculating energy in terms of M calories (Mcal) per kilogram of DM or the % of protein per kilogram of DM, as well as minerals or vitamin.

It is also important to take into consideration the percentage of first lactations and other factors and this can affect energy and protein density.

For example, if the herd has a high % of heifers, then the density increases as heifers eat less and are still growing.

With that being said, the diets tend to be more expensive and eventually, some cows with high DMI may gain too much condition.

However, it may still be difficult to compensate for a difference in DMI even with a high concentrated diet as mentioned above.

This will cause negative effects to the heifers as their reproductive performance may suffer.

They may not produce as much as their genetic potential would allow or may not grow as much during the first lactation as they could.

One way to combat this is to formulate a diet with higher energy density.

That way, even eating smaller amount of DM, the younger animals will receive sufficient nutrients.

On the cost point of view, cost of feed will increase as the levels of concentration increase.

Adult cows may not need such a high density diet a well as they can compensate by eating more feed.

Hence, one way to solve this is by separating the heifers from the adult cows and have a balance diet for the adult cows, which will allow for a cheaper diet per kg of DM.

TMR should be prepared for all animals in the barn.

When feeding heifers, extra supplement can be added such as fats, protein or grain.

This will make it easy to provide a diet suitable and well balanced for both groups of herd, while at the same time, take advantage of the higher DMI of adult cows and feed them a lower-cost diet.

DMI is a very import factor that affects milk production, feed costs and profitability.

In general, 1 kg per day increase in DM will help to produce 2 - 2.5 kg of additional milk.

Higher DMI will result in lower feed costs per unit of milk produced as lower or fewer nutrient dense feed can be used as a source of nutrients.

Therefore, it is crucial to properly adjust the diet depending if cows are eating more or less. If they are eating more, maybe fat can be reduced in the diet, whereas if the cows are eating less, the diet has to be more concentrated.

One of the challenges of DMI is that it is very difficult to know the actual DMI of individual cows in a barn.

One of the tool that can be used to help evaluate nutrition on single-TMR herds is body condition score.

Body condition score (BCS) can be used to evaluate nutrition and feeding management of early lactation cows in pen situations.

Cows in early lactation is expected to lose some BCS. A loss of 0.25 is good but if they lose more than 0.5, the fresh cows are not eating enough.

It is crucial to manage the farm in such a way that the DMI is not affected especially during fresh period.

Milk product is closely correlated to the DMI.

Cows which peak higher in early lactation produce more milk over the entire lactation cycle.

Hence, keeping a consistent, high quality, well balanced source of feed in front of the cows is crucial.